A standard desktop computer monitor or notebook PC shows about 100 pixels per inch. An iPad 2 tablet has a sharper screen with a PPI of 132.

Samsung ups the ante with devices like the Galaxy Tab 10.1, an Android tablet with a 1280×800 10.1-inch display. That’s a PPI of 149. Want more? Samsung’s Galaxy Tab 7.7 crams the same 1280×800 resolution into a 7.7-inch form factor. That’s a PPI of 197.

What? You want more? Apple’s iPad 3 shows 2048×1536 on a 9.7-inch screen, which computes out to a PPI of 264. And the iPhone 4/4S is 960×480, which is an amazing PPI of 326.

Photographs, text and icons on those high resolutions are stunning. But they are also consuming more bandwidth to transmit, more storage, more processing power, and more electrical power. The iPad 3’s battery is considerably larger than the battery in the iPad 2, and the iPad 3 also has a stronger GPU. Yet battery life and apparent performance are about the same. The new model needs more horsepower simply to break even.

High resolution is about more than tablets and phones. The Liliputing website reports that we’ll be seeing these types of displays everywhere—desktops and notebooks—in only a year or two. The site’s story “Intel: Retina laptop, desktop displays coming in 2013” says this is what Intel sees happening in the computer space over the next few years:

You should read the story; it does a good job of explaining the relationship between PPI and viewing distance, as well as the limits of “retina” displays. At some point, the human eye simply can’t perceive any improvement in resolution.